Избавление от пустого указателя/пустой строки оценивает в массиве C#

Я решил эту проблему, отредактировав копию ControlTemplate для элемента управления IntegerUpDown и добавив свойство isReadOnly в WaterMarkTextBox.

 <ControlTemplate x:Key="ControlControlTemplate1" TargetType="{x:Type Control}">
                <xctk:ButtonSpinner x:Name="PART_Spinner" AllowSpin="{Binding AllowSpin, RelativeSource={RelativeSource TemplatedParent}}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" ButtonSpinnerLocation="{Binding ButtonSpinnerLocation, RelativeSource={RelativeSource TemplatedParent}}" Background="{TemplateBinding Background}" HorizontalContentAlignment="Stretch" IsTabStop="False" ShowButtonSpinner="{Binding ShowButtonSpinner, RelativeSource={RelativeSource TemplatedParent}}" VerticalContentAlignment="Stretch">
                    <xctk:WatermarkTextBox IsReadOnly="True" x:Name="PART_TextBox" AutoMoveFocus="{Binding AutoMoveFocus, RelativeSource={RelativeSource TemplatedParent}}" AutoSelectBehavior="{Binding AutoSelectBehavior, RelativeSource={RelativeSource TemplatedParent}}" AcceptsReturn="False" BorderThickness="0" Background="Transparent" ContextMenu="{TemplateBinding ContextMenu}" Foreground="{TemplateBinding Foreground}" FontWeight="{TemplateBinding FontWeight}" FontStyle="{TemplateBinding FontStyle}" FontStretch="{TemplateBinding FontStretch}" FontSize="{TemplateBinding FontSize}" FontFamily="{TemplateBinding FontFamily}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" IsTabStop="True" IsUndoEnabled="True" MinWidth="20" MaxLength="{Binding MaxLength, RelativeSource={RelativeSource TemplatedParent}}" Padding="{TemplateBinding Padding}" TextAlignment="{Binding TextAlignment, RelativeSource={RelativeSource TemplatedParent}}" TextWrapping="NoWrap" TabIndex="{TemplateBinding TabIndex}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" WatermarkTemplate="{Binding WatermarkTemplate, RelativeSource={RelativeSource TemplatedParent}}" Watermark="{Binding Watermark, RelativeSource={RelativeSource TemplatedParent}}"/>
                </xctk:ButtonSpinner>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter Property="BorderBrush" Value="{DynamicResource {ComponentResourceKey ResourceId=ControlMouseOverBorderKey, TypeInTargetAssembly={x:Type Themes:ResourceKeys}}}"/>
                    </Trigger>
                    <MultiDataTrigger>
                        <MultiDataTrigger.Conditions>
                            <Condition Binding="{Binding IsReadOnly, RelativeSource={RelativeSource Self}}" Value="False"/>
                            <Condition Binding="{Binding AllowTextInput, RelativeSource={RelativeSource Self}}" Value="False"/>
                        </MultiDataTrigger.Conditions>
                        <Setter Property="IsReadOnly" TargetName="PART_TextBox" Value="True"/>
                    </MultiDataTrigger>
                    <DataTrigger Binding="{Binding IsReadOnly, RelativeSource={RelativeSource Self}}" Value="True">
                        <Setter Property="IsReadOnly" TargetName="PART_TextBox" Value="True"/>
                    </DataTrigger>
                    <Trigger Property="IsKeyboardFocusWithin" Value="True">
                        <Setter Property="BorderBrush" Value="{DynamicResource {ComponentResourceKey ResourceId=ControlSelectedBorderKey, TypeInTargetAssembly={x:Type Themes:ResourceKeys}}}"/>
                    </Trigger>
                    <Trigger Property="IsEnabled" Value="False">
                        <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                    </Trigger>
                    <Trigger Property="IsFocused" Value="True">
                        <Setter Property="FocusManager.FocusedElement" TargetName="PART_TextBox" Value="{Binding ElementName=PART_TextBox}"/>
                        <Setter TargetName="PART_TextBox" Property="Background" Value="{StaticResource LightGreyBrush}" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>

Чтобы отредактировать копию шаблона, щелкните правой кнопкой мыши элемент управления, затем отредактируйте шаблон, отредактируйте копию или текущую